It has been about two months since I was in Austin at my first Microsoft Exchange Conference. I must say Austin left quite an impression on me, partly because of the wonderful people and great music, but mostly because of the immensely passionate public folder customers I got a chance to meet. Public folders are one of the oldest living artifacts in Exchange Server and MEC was a reconfirmation that they continue to serve some critical and unique collaboration scenarios for our customers. MEC allowed me to meet with some of our largest and most complex public folder customers to discuss in great detail how some companies’ entire business processes rely on public folders.

At MEC, customers asked us for higher scale and more functionality in Exchange modern public folders. The 3 top asks in the order of priority for the public folder team included:

Scale improvements

OWA support for calendar and contacts

Better public folder reporting tools

What's new on scale?

As discussed at MEC, scaling up modern public folders is a priority for us. We have already made significant strides towards improving public folder scale. We have removed the design limitation which was the root cause for the hard limit of 10,000 total folders - this opens up new doors for scale. Synchronization of public folder hierarchy was a major component responsible for the 10,000 folder limitation. Full hierarchy sync has been improved to the point where it can scale linearly as folder count grows within the environment. There have also been storage optimizations which will provide better performance in operations on public folders in run state.

What does this mean for public folder counts?

The good news is that with these recent changes you can expect to see higher limits on public folders rolled out in the next few months. Office 365 customers should see the total folder limit increase to 100,000by early July. For our large on premises customers, we are targeting to increase this limit further with the CU6 release. As we get closer to the CU6 date we will publish an update on how far we were able to push the limit for on premises customers.

This is just the first round in the public folder scale improvements we are working to deliver. As we move forward with these improvements, our goal is to scale to at least 1 million folders. We are also looking into making improvements to migration as well as store more bytes in more public folder mailboxes with more users accessing them.

Why CU6?

Scale updates is complex business. Investigating and working through fixes on scale required a significant lead time and these updates didn’t fit into the CU5 timeline as work from multiple teams with features dependent on each other were involved. So we plan to roll in the above mentioned scale improvements in CU6 for our on-premises customers. Office 365 customers however will see these updates as soon as the code containing all of the necessary public folder scale improvements rolls out into service. This service update is targeted for early July, but as with all Office 365 updates some tenants will see it sooner than others until the service update has been deployed world-wide. We will be publishing another blog around the CU6 timeframe to share news about the next round of public folder scale updates.

What about the other asks?

We expect calendar and contact public folders support in OWA to follow the scale updates. We do not have exact timelines on these yet. Following calendar & contact folder support in OWA we will be working to deliver additional management tooling to assist in your management of public folders. Stay tuned for updates.

At Exchange we live to solve tough problems. Public folders were re-architected in Exchange 2013 to take advantage of the well proven mailbox design and deliver a solution for customers moving to Office 365 with public folders. We will continue building towards this promise as we proceed to meet customer requirements. Thanks to the customers who provided input at MEC. We will keep you updated with further details in advance on the Exchange Blog.

At this time, the team is working on folder limits specifically, because for all intents and purposes, this is a far more 'restrictive' limit than the number of PF mailboxes. With mailbox sizes that we can do both Online and on-prem, customers feel a lot more

constrained in number of folders than having PF mailboxes actually filled up.

That being said - can you help us understand what is driving the need for more PF mailboxes for you? The team is always open to feedback.

Let me first say, I would agree that folder limits are far more important than anything else. For hosted environments, having dedicated mailboxes for each customer are better for many reasons. Such as provisioning, throttling, reporting, isolation, etc. With

thousands of different customers in a single Exchange Org things can get a little tough sorting out which customer is where and when to move them around. We can definitely work with 100 mailbox limits, which would involve different customers sharing mailboxes,

@DJ, the PF mailbox limit is something the team is already investigating, but we have nothing to share at this time with regards to that particular item. We know our hosting customers are fond of the scale-out model and welcome their feedback on how they

I have over 15000 public folders, with more than 50% mail enabled. By all means, please focus on only 1/2 of the problem. I will just sit over here staying at Exchange 2010. By the time I get to upgrade (if ever), it will be to 2015 or beyond.

Being as our business is project based, every project has both a network folder structure, and a public folder structure (which is mail enabled by the project number as the email address). That allows people to simple CC: the public folder address for all communications

related to the specific project.

Saving each an every email of every project out into the network file shares would be beyond both the user's capability (every .msg would have 100's of characters for file names), and would be an administrative nightmare to try and manage.

There isn't any better mechanism for 'collecting' this information that I have ever found. Lord knows I've looked... and looked... and prayed..

I would love to look at Sharepoint to replace all of this, but hey.. guess what email saving mechanism that uses?

Thank you for the continued commitment to make Office 365 better! This makes a large migration I am currently focused on have one less area to worry about. I cannot stress how important it is to customers to hear the news that another feature area has

got focus and resolution. Yall are doing a great job improving the story for today and tomorrow!

Hi Kanika- thanks for the post and details. My nonprofit recently migrated from on-premise Exchange to Office 365 and were shocked that our Shared Contacts and Calendars under Public Folders simply aren't accessible from the Office 365 web experience!

It's a major step back for us and a significant hit to productivity. So, it's good to hear it's on the radar to enable OWA for public folders containing Calendar and Contacts. I know you can't give exact dates, but I'm not too familiar with the timing on planning

CU6 release and what a subsequent timeframe might be. Can you give some general guidance as to when these items in public folders might be available via OWA? thanks